Tommy Ly:
Eventually it feels like I'm approaching nothingness, like consciousness is fading...fading, there was a moment yesterday where consciousness seemed to shrink into a little dot. I don't know if I'm getting really close here. And then a thought disturbs that emptiness / concentration.
This reminds me of my own experience, so I will share how it is for me, in case it may turn out to be useful for you too.
I used to make this mistake: I reached the 7th jhana aspect of High Equanimity, got fascinated with it, and solidified the sensations of Nothingness, crossing over to the jhana side of the experience. That was a dead end (at least from the point of view of getting a Fruition). I had to remind myself to constantly focus on one of the 3C, dukkha at the time, and that usually unlocked a Fruition. Your description makes it look a lot like what I was going through. The gradual feeling of consciousness shrinking might be making Nothingness "harder", or moving to NPNYNP / 8th jhana. Instead, analyse the sensations that make up Nothingness, you might be able to see the little bubbles of stuff Nothingness is composed of. See the 3C in these bubbles to keep vipassanising the process.
For me, getting Fruitions is a lot about balancing effort and just letting the process do itself. It is a bit delicate and tricky to do. To much letting go, and I drift off. Too much effort, and I tense up and the process gets stuck. I would suggest to try alternating effort and trusting the process as needed. Occasionally, getting distracted for a few seconds and remembering to go back to practice is what actually triggers the fruition, which for me is a sign of too much effort: the fruition comes up when I let my guard down, so to speak.
EDIT: This is how I described the mistake at the time, and how I worked around it (I already had SE at the time, and was working on repeat fruitions)
Start from A&P, pass through DN, get into vibrating EQ, near miss, high EQ, pass through infinite space and infinite consciousness*, get to nothingness (7th), so far so good.
Tell myself this is leading to a cessation, so work on the feeling of nothingness, increase it, deepen it, watch a lot of things disappear, cling to all that nothingness... I was solidifying nothingness(!) super hard. Might be the way to get to NPNYNP, but not what I was aiming for...
Restart.
Start from A&P, pass through DN, get into vibrating EQ, near miss, high EQ, pass through infinite space and infinite consciousness*, get to nothingness (7th), so far so good. Wait.
Remember direct experience of how sukha is an upsetting factor, which I had to let go of to move up from 3rd jhana to 4th jhana. Recognise how every single feeling, thought, desire, sense of time... they are all propping up attachment, craving for equanimity itself. Which makes the equanimity of "knowledge of equanimity about formations" kind of incomplete, kind of not real equanimity.
Start to "debunk" each single formation as upsetting and unworthy of attention.
Notice how "I" reacts by trying to super-solidify something, anything, to prop up this preposterous sense of self. It may have been a feeling of the hand being there all nice and tingly (look, it seems solid, but it is made up of tiny vibrations, meaningless, they are not even touch or an idea, they do not contain a sense of self, sticking to them doesn't satisfy you). Then it may have been the feeling of tension / craving / aversion to keep working (look, if you notice that tension, it is a feeling, it is not you being tense, a sensation cannot watch another sensation). Then it may have been a sound (look, how desperate are "you" to cling to a sound, see?, it's vanished already). All the while "everything" getting more still, darker, more devoid of meaning...
...and then a tiny discontinuity. Something like remembering having blacked out even further, a little bit, for a fraction of a second, while getting a feeling of release, like someone is turning on the lights again, "everything" going back in its place. Kind of like a little bit of work was done.
Discontinuity? Cessation? Not the "big blip" that I experienced at night during retreat: that one was spectacular, like being dead for a fraction of a second**, deeper, somehow perhaps "longer" (however much it makes sense to talk of time during that). But this one was in its right place, in its right time, with its right understanding of the three characteristics.
Actually, I've managed to get a second one repeating all these steps.
I'll see if the experience can be reproduced, with what results.
(Repeated experiments seemed to confirm that those were, indeed, fruitions.)
Any attitude, expectation, mood that feels like it's part of the solid "you" that's looking at things arising and passing away also needs to be seen as arising and passing away and being part of that whole mish-mash of arising and passing. In other words: throw it all in the hopper. 
